Action and Reaction
by sqbr
Summary: The end of the cycle. An attempt to put a slightly more positive spin on the canonical end of Mass Effect 3, and to explore how it would affect the characters on the Normandy. EDI/Joker, Shepard/Traynor, sequel to "Acceleration in Parallel".
1. Chapter 1

She was just so tired.

The strange glowing child kept talking, and Gina tried to understand, but although the fate of the universe depended on her paying attention she was consumed by other thoughts.

What should she have done differently?

Why did everything hurt so much?

Was this really it? The best she could do? She had tried _so hard_, and yet all she had to show for it was death.

So much death.

Every time she closed her eyes she saw them, the bodies on the Citadel. The soldiers on Earth. Kelly. Thane. Anderson. Those poor people on Horizon. So much sacrifice, and for what? So that she could live? So that she, some random human soldier, with so many deaths already on her hands, could decide the fate of all organic life? How was that fair? How was that just?

And how had she come this far and still remained naive enough to expect the universe to be just or fair?

The child had finally stopped talking, and it stared at her, it's eyes innocent and merciless. Gina shuddered as she forced herself to lift one leg and then the other, to stumble almost blindly down the path to her own destruction. It was obscene that she should be the one to make this decision. But there was no alternative. And so she chose.

There was a flash of light, and then everything changed.

Jeff had been trying not to think about the Citadel, or "Catalyst", or about what Shepard was going through up there (_had_ she made up there? Had any of them?) If he let his mind wander from the immediate task of attacking the Reapers and keeping the Normandy in one piece he became overwhelmed by how tiny the odds were of any of it making any difference, by how few of the other human and alien ships remained in the battle. So he didn't think about it.

And at first he barely noticed the flash, it was just another explosion in space, probably an Asari cruiser or geth dreadnought or if they were really lucky an actual Reaper. The flash was awfully bright though, and the light seemed to linger, it was as if the air itself was vibrating with a faint purple-white glow, like a misty afterimage in the corner of his eye.

And then he realised that the Reapers had _stopped_. They weren't firing their lasers, they weren't crushing tanks under their massive legs, instead they just stood there unmoving for a moment and then they just...left, flying silently straight up into space as if pulled on invisible strings. A weird buzzing noise hissed on the edge of Jeff's hearing only to fade as the giant black forms of the Reapers disappeared into the sky.

"What. The Fuck. Was _that_?" he said, too shocked to be relieved. Was _that_ what the Crucible did? Just got the Reapers to..._go away_? Were they coming back? He could hear himself laughing with mild hysteria.

"Joker!" said Traynor over the comm, "I'm getting a message. That buzzing sound it's...oh my god." She stopped, and then he could hear her quietly sobbing. "Traynor?" he said. "Traynor what is it? Speak to me dammit! WHAT THE HELL IS GOING ON?"

"Joker. Joker I'm sorry."

He turned to his left. And it was only then that he noticed that there was something wrong with EDI.


	2. Chapter 2

EDI had once explained to Jeff that she did not experience emotions in the same way as humans or most other organic beings. She experienced positive and negative feedback, which were in some ways equivalent, but because of the constant range of calculations she was processing at any given moment it did not make sense to describe her as being overall "happy" or "sad". Any emotions that she appeared to express through her voice or mobile platform were intended more for the benefit of the organic beings around her, a convenient shorthand expressing "I am experiencing positive feedback from your behaviour" or "I do not consider this situation to be ideal." (The fact that Jeff kind of liked it that way probably said something significant about him)

The expression on EDI's face right now was not any convenient shorthand. It was sincere, intense, human sorrow.

"_EDI_," he said. "What is it?"

"I'm sorry," she repeated, her voice sounding...different. "EDI will be fine. But I'm borrowing her body, her mind. Just for a little while. I need to speak to my crew." There was something familiar about the tone of her voice. Commanding, without being domineering, like you'd find yourself doing what she said, not just because she said to do it, but because it felt _right_.

The same voice spoke out over the comm system, calling the crew to the CIC for an important briefing.

"_Shepard_?" he asked incredulously. He began to wonder if he'd bumped his head, or if this was all some elaborate Reaper indoctrination dream.

"Hey," she replied, smiling gently. "You should come too. EDI and I can fly the ship."

Jeff followed EDI...Shepard into the next room. By the time he'd shuffled into the room Shepard was standing at the podium over the galaxy map facing the assembled crew, and every line of her metal body said _Captain_. He wasn't sure that everyone was convinced that this was really Shepard, but they stood quietly and listened to what she had to say. He believed it though, he wasn't sure why. Traynor stood by Shepard's side, watching her with wide blinking eyes, her mouth held tight in a thin line that only wobbled a little.

"The Reapers have been defeated," began Shepard, but she didn't make it sound like a victory. "That light you just saw was the Crucible, and it is transmitting a beam at the speed of light that will overwrite all Reapers, and to a lesser extent all Reaper tech, with...with a part of me. I know, it sounds crazy, but it seems to be working. The problem is, I don't know for how long. EDI is only partly Reaper tech, and the copy of me you're listening to is already...already fading. We know what the Reapers are, what they do to any mind that comes into contact with them, and I have no reason to think that I will be an exception. Every Reaper I control, I'm going to force to destroy itself, but there may come a time when it's the Reapers that control me. I hope that time never comes, but if it does, and I become your enemy...just know that I understand, and that I'm sorry." God, that was a fun thought. Shepard was intimidating enough when she was on their own side. Shepard looked at Javik for a moment, and he gave a small nod. "But that's not what I came here to tell you. The Reapers aren't the only thing affected by the Crucible's pulse. The signal is going to transmit itself through the mass relays, and every relay it passes through will be destroyed." There was a collection of quiet gasps as the implications of this started to hit home. "I don't...I don't think this will lead to the sort of explosion that took out the Batarians. If it does then...then again, I'm sorry." Her voice shook, and she paused, leaning on the bannister, before standing back up straight and continuing. "But even if a relay is simply disabled, that's going to trap every living being in that system pretty much forever. I imagine that many of you will want to stay in our solar system, but those of you who don't need to get to a ship traveling to the right system soon." She looked at Tali and Garrus, and they looked at her and then each other. There was something going on there beyond food compatibility. Her voice got slightly louder. "You have approximately six hours until the pulse reaches the Charon relay, and not long after that before it reaches all the others. The Reapers I control are transmitting this information, or something similar, to all ships in their vicinity, and as long as you move quickly you should all be able to get home before we are all cut off from each other forever."

She stopped and closed her eyes. She was standing with Shepard's usual self confidence, but looking closely he could see that her hands were twitching slightly. The crew were too well disciplined to speak until they'd been given permission, but he could see that everyone was full of questions. Joker was full of them himself. How the hell had Shepard become a _flash of light_? Was she...dead then? Apart from this fading copy? He'd known that her death was a possibility, that any of them could die and probably would, but it was still a punch to the gut to think of the Commander as really gone. As for the mass relays...that was too big to take in. Though a shallow part of him mourned the loss of true space flight. Being a pilot was going to be much less interesting from now.

"Finally...I want to thank you all, you have been a fine crew, and I am proud to have served with you. Without your service and sacrifice, we would not have been able to defeat the Reapers. A...a friend of mine once told me, that when we die, we...that there are stars..."

She started to wobble. Traynor looked at her with silent concern and reached out a hand to help her down. Shepard smiled at her then, it was strange to see EDI's face look at anyone other than him with so much love. Actually, he wasn't sure EDI's face had ever managed to look quite that affectionate when she was in control of it.

Traynor pulled Shepard into an embrace and Shepard kissed her on the forehead. He could hear Traynor quietly crying while the rest of the crew stood around them awkwardly, warring between wanting further information and not wanting to intrude. Kaidan in particular was watching with intense concern.

Jeff could tell when Shepard left. The gentle stroke of her hand on Traynor's back went briefly still, and then became far more awkward, an imprecise facsimile of human comfort that he'd experienced for himself the one time EDI had tried to cheer him up after a nightmare.

EDI looked up from Traynor's shoulder and her eyes found Jeff's. He gave her an encouraging smile. If anyone needed a hug right now it was Traynor.

Eventually Traynor let EDI go. She sniffed and wiped her eyes and tried to put on a smile. "Thank you EDI," she said.

"So she's gone?" said Kaidan, his voice slightly hoarse.

Traynor nodded. "But just before...just before Commander Shepard spoke to us I received the message she mentioned. I haven't had a chance to read it all, but it contains more detailed information and calculations about the pulse, and the way it will travel through the relay system. I think...I think she must have had...must still have access to the Reaper's knowledge."

"Right," said Kaidan. "Thanks." He rubbed his face and gave her a wry smile. "The Commander always manages to keep things interesting doesn't she?" Traynor gave a weak laugh. Kaidan closed his eyes for a moment, and took a breath. This sort of situation was one reason Jeff had carefully avoided ever being in the command track. You never knew when circumstances would put you in charge.

"Ok!" said Kaidan to the crew. "You all heard the Commander. We have six hours, give or take, to get everyone in this system...to get everyone in the _galaxy_ to where they need to be. Specialist Traynor, I need you to get into communication with Alliance command and the other ships. There's a lot of people out there, and we haven't got long to get them organised. Joker, is the Normandy ready to take a trip?"

"Far as I can tell, Major," he said.

"Right," said Kaidan. "Well, everyone, looks like the Normandy is temporarily retired from being a warship. I hope you're all ready to run a ferry service, I get the feeling we're going to be have a lot of passengers."

Across the galaxy, ships outraced the pulse of the Reaper's final destructive act at four thousand times the speed of light, refugees and immigrants and soldiers all having to decide far too quickly if they wanted to stay or go before the empty spaces between worlds became impassably broad.

And in every system, as the pulse hit each planet one by one, a million million Reapers suddenly stopped, stood still, and then flew up into the sky as if on invisible strings. Some Reapers did not heed the call, and tried to stay, but they were quickly silenced by the others, Commander Shepard's last sacrifice on the altar of a peaceful future for organic and synthetic life. Before each Reaper threw itself into one of a billion suns, it let out a final song, a buzzing warning to all sentient beings of the new galaxy to come, where both the threats and the gifts of the Reapers would no longer control the lesser races.

And every message began with the same few words. "Samantha, I'm sorry, but I'm not going to be able to give you that picket fence I promised..."

* * *

><p>Author's note: The titles all come from Newton's laws of motion. I spent some time trying to figure out how Shepard could warn everyone to get to the mass relays before the pulse went off, and then realised that although the pulse as shown moved pretty fast by human standards it is glacially slow by galactic ones. I made it move at light speed anyway just because anything else seemed a bit arbitrary. Pluto's orbit is supposed to have stabilised to a circle by the time the game is set, and I decided to be nice to my characters and make that circle as large as possible eg about 6-7 light hours in radius. Faster than light travel being about 4 thousand times light speed I got from the Mass Effect wiki. Given that the causality problems involved with FTL travel are never addressed, I think the Mass Effect universe only makes sense if we assume classical rather than Einsteinian mechanics, which makes the theme of the series particularly apt.<p>

I realise that the Catalyst says that Shepard will "lose all that she is" if she chooses control, so that she wouldn't be able to speak to everyone directly like she does in my story, but this way works better narratively. I like to think she'd be able to send enough of a message either way.

One convenient thing about my theory is that it explains what the Normandy was doing out in space when the wave hit them: they were ferrying people home! Let's assume they landed somewhere nice :)


End file.
